How to put a Linear Workflow in practice with Cycles
By default, Blender is a scene referred radiometrically linear reference space model.

This means that, when Cycles is selected as the renderer, values are radiometrically linear ratios that extend from zero to infinity.

The subject of color, color management, scene and display referred, and other such topics is immensely vast, far too vast for a simple answer here.

The short answer to your query however, is that Cycles is already a scene referred renderer, and no special effort is required to enable this aspect. More specifically, if you load an sRGB display referred image as a texture, it will be automatically linearized to display linear. While not scene linear, this permits textures to behave within a scene referred system.

Upon loading images in common formats such as JPEG, TIFF, PNG, etc. you should not adjust your image nor adjust your output. The linearization happens at the architectural level, and is correctly formatted for output.

To fully harness a scene referred model though, one should begin to round out their knowledge of color. A wonderful entry point might be the Visual Effects Society paper written by Jeremy Selan titled Cinematic Color: From Your Monitor to the Big Screen.